The role of ions in the regulation of protein synthesis by mammalian cells will be investigated. Results obtained with extracts of mammalian cells suggest that chloride may specifically inhibit the initiation of protein synthesis above a critical concentration. Variations in the chloride content of cells may be relevant in determining the rate of protein synthesis under different physiological conditions. Experiments directed at studying the role of interferon in the defense of mammalian cells against viral infections are planned. These experiments are made possible by the development of cell free protein synthesizing systems which show activities comparable to those of intact cells. The effect of double stranded RNA on human cells treated with interferon will be evaluated with regard to the translation of specific viral templates. BIBLIOGRAPHIC REFERENCES: B. Moss, A. Gershowitz, L.A. Weber and C. Baglioni, Histone mRNAs contain blocked and methylated 5' terminal sequences but lack methylated nucleosides at internal positions. Cell, 10, 113-120 (1977). Hickey, E.D., Weber, L.A., Baglioni, C., Kim, C.H., and Sarma, R. A Relationship Between Inhibition of Protein Synthesis and Conformation of 5'-Phosphorylated 7-Methylguanosine Derivatives. J. Mol. Biol. 109, 173-183 (1977).